Description

If using WebSockets, it always throws the NPE below:

Unexpected RuntimeException
Last cause: null
Stacktrace
Root cause:
java.lang.NullPointerException
at org.apache.wicket.markup.html.form.Form.onComponentTag(Form.java:1520)
at org.apache.wicket.Component.internalRenderComponent(Component.java:2511)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1488)
at org.apache.wicket.Component.internalRender(Component.java:2370)
at org.apache.wicket.Component.render(Component.java:2298)
at org.apache.wicket.ajax.XmlAjaxResponse.writeComponent(XmlAjaxResponse.java:127)
at org.apache.wicket.ajax.AbstractAjaxResponse.writeComponents(AbstractAjaxResponse.java:214)
at org.apache.wicket.ajax.AbstractAjaxResponse.writeTo(AbstractAjaxResponse.java:145)
at org.apache.wicket.ajax.AjaxRequestHandler.respond(AjaxRequestHandler.java:363)
at org.apache.wicket.request.cycle.RequestCycle$HandlerExecutor.respond(RequestCycle.java:840)
at org.apache.wicket.request.RequestHandlerStack.execute(RequestHandlerStack.java:64)
at org.apache.wicket.request.RequestHandlerStack.execute(RequestHandlerStack.java:97)
at org.apache.wicket.request.cycle.RequestCycle.execute(RequestCycle.java:254)
at org.apache.wicket.request.cycle.RequestCycle.processRequest(RequestCycle.java:211)
at org.apache.wicket.request.cycle.RequestCycle.processRequestAndDetach(RequestCycle.java:282)
at org.apache.wicket.atmosphere.EventBus.post(EventBus.java:320)
at org.apache.wicket.atmosphere.EventBus.postToSingleResource(EventBus.java:297)
at org.apache.wicket.atmosphere.EventBus.post(EventBus.java:272)
at com.soluvas.story.impl.StoryManagerImpl.publish(StoryManagerImpl.java:107)
at id.co.bippo.comment.story.ProductCommentedStoryPoster.createStoriesAndPublish(ProductCommentedStoryPoster.java:71)
at java.lang.reflect.Method.invoke(Method.java:601)
at com.google.common.eventbus.EventHandler.handleEvent(EventHandler.java:74)
at com.google.common.eventbus.SynchronizedEventHandler.handleEvent(SynchronizedEventHandler.java:45)
at com.google.common.eventbus.EventBus.dispatch(EventBus.java:314)
at com.google.common.eventbus.AsyncEventBus.access$001(AsyncEventBus.java:34)
at com.google.common.eventbus.AsyncEventBus$1.run(AsyncEventBus.java:100)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:722)
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Another stacktrace:

Unexpected RuntimeException
Last cause: null
Stacktrace
Root cause:
java.lang.NullPointerException
at org.apache.wicket.markup.html.form.Form.onComponentTag(Form.java:1520)
at org.apache.wicket.Component.internalRenderComponent(Component.java:2511)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1488)
at org.apache.wicket.Component.internalRender(Component.java:2370)
at org.apache.wicket.Component.render(Component.java:2298)
at org.apache.wicket.ajax.XmlAjaxResponse.writeComponent(XmlAjaxResponse.java:127)
at org.apache.wicket.ajax.AbstractAjaxResponse.writeComponents(AbstractAjaxResponse.java:214)
at org.apache.wicket.ajax.AbstractAjaxResponse.writeTo(AbstractAjaxResponse.java:145)
at org.apache.wicket.ajax.AjaxRequestHandler.respond(AjaxRequestHandler.java:363)
at org.apache.wicket.request.cycle.RequestCycle$HandlerExecutor.respond(RequestCycle.java:840)
at org.apache.wicket.request.RequestHandlerStack.execute(RequestHandlerStack.java:64)
at org.apache.wicket.request.RequestHandlerStack.execute(RequestHandlerStack.java:97)
at org.apache.wicket.request.cycle.RequestCycle.execute(RequestCycle.java:254)
at org.apache.wicket.request.cycle.RequestCycle.processRequest(RequestCycle.java:211)
at org.apache.wicket.request.cycle.RequestCycle.processRequestAndDetach(RequestCycle.java:282)
at org.apache.wicket.atmosphere.EventBus.post(EventBus.java:320)
at org.apache.wicket.atmosphere.EventBus.postToSingleResource(EventBus.java:297)
at org.apache.wicket.atmosphere.EventBus.post(EventBus.java:272)
at com.soluvas.story.impl.StoryManagerImpl.publish(StoryManagerImpl.java:107)
at id.co.bippo.comment.story.ProductCommentedStoryPoster.createStoriesAndPublish(ProductCommentedStoryPoster.java:71)
at java.lang.reflect.Method.invoke(Method.java:601)
at com.google.common.eventbus.EventHandler.handleEvent(EventHandler.java:74)
at com.google.common.eventbus.SynchronizedEventHandler.handleEvent(SynchronizedEventHandler.java:45)
at com.google.common.eventbus.EventBus.dispatch(EventBus.java:314)
at com.google.common.eventbus.AsyncEventBus.access$001(AsyncEventBus.java:34)
at com.google.common.eventbus.AsyncEventBus$1.run(AsyncEventBus.java:100)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:722)
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This bug is always reproducible in my configuration.

It doesn't occur if comet/long-polling is used instead of websockets. Which means setting below will not trigger the bug: